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electrical:12v:alt_and_solar [2025/01/07 17:09]
frater_secessus [how alternator charging helps] |
electrical:12v:alt_and_solar [2025/08/23 22:14] (current)
frater_secessus [putting it all together] |
| Alternator charging is extremely powerful and cheap compared to typical solar installs. It works best when solar works worst: when the batteries are deeply discharged in the morning. The sun is weak then but the bank needs a large supply of current (early [[electrical:12v:charging#bulk_stage|Bulk charging]]). | Alternator charging is extremely powerful and cheap compared to typical solar installs. It works best when solar works worst: when the batteries are deeply discharged in the morning. The sun is weak then but the bank needs a large supply of current (early [[electrical:12v:charging#bulk_stage|Bulk charging]]). |
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| [[electrical:solar:charge_controller#pwm|PWM]] controllers are [[electrical:solar:pwm_tweaking#pwm_s_achilles_heel|somewhat hamstrung in this scenario]]; since they run the panels ~at battery voltage((for the purposes of this discussion)) (Vbatt) they produce the least power exactly when the most power is required. Pushing up bank voltage with the alt helps the PWM make more power. | [[electrical:solar:charge_controller#pwm|PWM]] controllers are [[electrical:solar:pwm_tweaking#pwm_s_achilles_heel|somewhat hamstrung in this scenario]]; because they run the panels ~at battery voltage((for the purposes of this discussion)) (Vbatt) they produce the least power exactly when the most power is required. Pushing up bank voltage with the alt helps the PWM make more power. |
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| Alt charging shovels current into the bank until Valt is reached, at which point it begins to taper off. Solar can take it from there. A good metaphor might be a two-stage rocket: the alternator does the heavy lift getting the rocket off the ground then the solar charging takes care of the high altitude, high speed duties. | Alt charging shovels current into the bank until Valt is reached, at which point it begins to taper off. Solar can take it from there. A good metaphor might be a two-stage rocket: the alternator does the heavy lift getting the rocket off the ground then the solar charging takes care of the high altitude, high speed duties. |
| ===== optimal alternator contribution ===== | ===== optimal alternator contribution ===== |
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| Broadly speaking, //alternator charging is most effective in the morning// and //solar charging is most effective at local solar noon//. This pattern is most evident when using isolators/relays and/or lead chemistry batteries, and less evident when using [[electrical:12v:b2b|DC-DC chargers]] and/or lithium chemistries. | Note: this section talks about alternator contribution but also applies to generators. |
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| | Broadly speaking, //alternator charging are most effective in the morning// and //solar charging is most effective at local solar noon//. This pattern is most evident when using isolators/relays and/or lead chemistry batteries, and less evident when using [[electrical:12v:b2b|DC-DC chargers]] and/or lithium chemistries. |
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| There are several factors in play here. | There are several factors in play here. |
| ==== putting it all together ==== | ==== putting it all together ==== |
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| Alternator((or generator)) charging is most helpful/efficient((Ah replaced for a given amount of engine runtime)) in the morning when the bank voltage and state of charge are lowest. This may mean shifting driving errands to mornings or rainy days. | Alternator (or generator) charging is most helpful/efficient((Ah replaced for a given amount of engine runtime)) in the morning when the bank voltage and state of charge are lowest. This may mean shifting driving errands to mornings or rainy days. |
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